You've just described quite a few software problems. They don't exist because things were too simple, they exist because something that was essentially simple got made complex. One of my better tools to deal with projects that have run into trouble is to mercilessly cut stuff away.

One such case I was permitted to write about (most of my work is under NDA), I can't believe it's already been 8 years since then:

https://jacquesmattheij.com/saving-a-project-and-a-company/